Accelerating the rapid development of new energy sources such as wind power is a key path to achieve the “dual carbon” goals. However, with the approaching wave of wind power decommissioning near the end of the 14th Five-Year Plan, China will face the challenges of large-scale wind power decommissioning and reconstruction, which will seriously threaten the power system’s supply adequacy and flexibility. In this context, coal power remains an important cornerstone for power supply security and flexible regulation, necessitating coordinated development of wind power and coal power. To this end, a multi-stage coordinated planning method for low-carbon power systems considering wind power decommissioning and reconstruction and coal power flexibility upgrades is proposed. First, a model for direct decommissioning of wind power and orderly decommissioning of life extension retrofit considering system supply adequacy is established. A multi-path in-situ reconstruction scheme of wind farm is then proposed, featuring "large replacing small” and “capacity-equivalent retrofit expansion upgrades”. On this basis, considering the impact of coal power flexibility upgrades on new energy consumption, a coordinated planning model of wind power and coal power upgrades is constructed. Finally, a case study using the improved IEEE 39-bus system shows that the proposed method can provide wind power decommissioning and reconstruction schemes to ensure system supply adequacy. In addition, coal power flexibility upgrades can effectively meet the flexibility demands following wind farm expansions.